The present invention relates to a semiconductor device in which a semiconductor chip or an electrical component such as a chip capacitor is stacked on another semiconductor chip having a different function, and to a liquid crystal module provided with such a semiconductor device.
The conventionally available TCP (Tape Carrier Package) is an example of a semiconductor package for use in liquid crystal driving drivers.
For example, FIG. 11 and FIG. 12 show a TCP as a semiconductor device in which a semiconductor chip 112 is mounted in a device hole 121a which is formed at a predetermined position of a polyimide substrate 121 which is provided as an insulating base material tape.
The semiconductor chip 112 is electrically connected, via bumps 13 made of gold (Au), to inner leads 124 on the signal input side and inner leads 125 on the signal output side which project into the device hole 121a, on the opposite side of the surface of the polyimide substrate 121 where a conductive wiring (inner leads 124 and 125 and outer leads 126 and 127) is formed.
On the wiring pattern of the inner leads 124 and 125 and the outer leads 126 and 127 is formed an organic insulating film as a solder resist 122 to be patterned in a predetermined manner. Further, as shown in FIG. 12, surrounding the bonding portion between the semiconductor chip 112 and the inner leads 124 and 125 is a sealant 130 made of insulating resin.
Incidentally, with the wide spreading of portable phones in recent years, the TCP has been used as a semiconductor package for a driver (liquid crystal driver) for driving a liquid crystal used in portable phones. Such a liquid crystal driver for portable phones has been mass-produced by employing a semiconductor device which includes an SRAM in a single semiconductor chip, or a semiconductor device with a dual-function of a segment driver and a common driver.
However, a problem associated with installing the SRAM or the segment and common drivers in a single semiconductor chip is that the size of the entire semiconductor chip is increased. Further, when the semiconductor chip employs the common driver in particular, the voltage used in the common driver becomes relatively high, and this requires a high voltage resisting capability, which makes the application of a fine process difficult.
Further, as the portable phone liquid crystal module is made compatible with color display or fine-pitch display, the number of outputs is increased in the segment driver and the common driver. In this case, while the chip size can be reduced by a fine process on the SRAM side, manufacture by a fine process is impossible on the side of the common driver and the segment driver because they include a logic circuit. That is, the segment driver or common driver is preferably manufactured by a rough process of about 0.5 xcexcm, and the driver size cannot be reduced.
Further, since the semiconductor chips are manufactured from a single wafer process, the semiconductor chips need to employ the rough process as a whole, which is suitable for manufacture of the common driver and the segment driver. Thus, when a single semiconductor chip is to include the SRAM or the segment and common drivers, the chip size of the semiconductor chip is increased, resulting in increase in cost.
Further, driving of the liquid crystal module requires peripheral components, other than the liquid crystal driver, such as a chip capacitor. Such a peripheral component mounted on a carrier tape increases the size of the TCP itself, and, in turn, the size of the liquid crystal module.
Further, in order to mount the chip capacitor on the carrier tape, first, a solder-plated land is formed on the carrier tape, followed by forming a solder on the land by printing using a mount device. Then, the chip capacitor is placed on the solder for reflow soldering. Thus, mounting the chip capacitor on the carrier tape increases the number of assembly steps, and thus the cost.
In view of foregoing problems, for example, Japanese Unexamined Patent Publication No. 183102/1993 (Tokukaihei 5-183102) (published date: Jul. 23, 1993) discloses a semiconductor device in which two semiconductor chips are stacked on a carrier tape.
As shown in FIG. 13, the semiconductor device of the foregoing publication includes a flexible film 201 having first inner leads 204 and second inner leads 205 which are formed on one surface of the substrate and project into an opening 201a of the substrate with different lengths. This semiconductor device is manufactured by the process as shown in FIG. 14(a) through FIG. 14(d).
That is, as shown in FIG. 14(a) and FIG. 14(b), a first semiconductor chip 211 and the first inner leads 204 are electrically bonded with each other by gang bond, and as shown in FIG. 14(c) and FIG. 14(d), a second semiconductor chip 212 and the second inner leads 205 are electrically bonded with each other by a single point bond on the opposite side of the first semiconductor chip 211. The semiconductor device thus manufactured has a stacked structure of two semiconductor chips on a single plane.
In the semiconductor device having the foregoing structure, the stacked semiconductor chips can be adapted to have different functions, for example, by adopting the function of the liquid crystal driving segment and common drivers for one semiconductor chip and the function of the SRAM for the other semiconductor chip. This makes it possible to reduce the chip area compared with the case where the two functions are included in a single semiconductor chip.
However, in the semiconductor device of the foregoing publication, as show in FIG. 14(c), the bonding between the second semiconductor device 212 and the second inner leads 205 are carried out on the side of the first semiconductor chip 211 which is bonded with the first inner leads 204. Thus, considering a possible damage or other adverse effects on the first semiconductor chip 211, the bonding has to be made by a single point bond. This increases the time required for bonding the second semiconductor chip 212 and the second inner leads 205. As a result, manufacturing time of the semiconductor device is greatly increased.
Further, as shown in FIG. 12, the inner leads 124 and 125 bonded with the semiconductor chip 112 are usually bent to have a function of a dumper against an external force which acts on the semiconductor chip 112, so as to prevent wire breakage between the inner leads 124 and 125 and the semiconductor chip 112.
In contrast, in the semiconductor device of the foregoing publication, the first semiconductor chip 211 and the second semiconductor chip 212 are face to face and are connected to the first inner leads 204 and the second inner leads 205 of different lengths. Further, the first inner leads 204 and the second inner leads 205 are held nearly horizontally with respect to the wiring bearing surface of the flexible film 201. That is, the inner leads cannot have the dumping function. Thus, when an external force acts on the semiconductor chip to pull it, wire breakage easily occurs between the semiconductor chips and the inner leads.
Thus, when the semiconductor device of the foregoing publication is applied to the liquid crystal module, while the size of the device can be reduced compared with the semiconductor device having two functions (segment driver and common driver) in a single semiconductor chip, reliability of the liquid crystal module suffers by the susceptibility of wire breakage between the semiconductor chips and the inner leads.
The present invention was made in view of the foregoing problems, and it is an object of the present invention to provide a semiconductor device which requires a notably less manufacturing time by bonding a semiconductor chip or an electrical component (such as a semiconductor chip) and inner leads in a shorter period of time, and which is less susceptible to wire breakage between the semiconductor chip or the electrical component and the inner leads, and also to provide a small and highly reliable liquid crystal module using such a semiconductor device as a liquid crystal driving driver.
In order to achieve the foregoing object, a semiconductor device according to the present invention includes a carrier tape composed of a base material with a wiring pattern; inner leads which project into an opening of the carrier tape and which are connected to the wiring pattern; a semiconductor chip which is bonded with the inner leads at the opening; and an electrical component which is bonded with the inner leads on the opposite side of a surface of the semiconductor chip bonded with the inner leads, wherein the electrical component is bonded with the inner leads at a depression which is created as a result of bonding between the semiconductor chip and the inner leads.
With this arrangement, since the depression is formed as a result of bonding between the semiconductor chip and the inner leads, the inner leads have bent portions.
In this way, even when the semiconductor chip and the electrical component are pulled by an external force, the bent portions of the inner leads act as a dumber to prevent wire breakage between the semiconductor chip and the inner leads.
Further, since the electrical component stacked on the semiconductor device is bonded with the inner leads at the depression which is created as a result of bonding between the semiconductor chip and the inner leads, the semiconductor device can be made thinner than the case where the semiconductor chip and the electrical component are simply stacked.
As a result, reliability of the semiconductor device can be improved and the size thereof can be reduced.
Further, when the electrical component stacked on the semiconductor device is another semiconductor chip which has a different function from that of the semiconductor chip, one of the semiconductor chip can be adapted to have a function of a liquid crystal driving segment driver and the other semiconductor chip a function of a liquid crystal driving common driver, so as to be applicable to a liquid crystal module for use in liquid crystal display devices.
In this case, since wire breakage between the semiconductor chip and the electrical component is prevented in the foregoing semiconductor device, the semiconductor device can be appreciably used as a liquid crystal driving driver to provide a small and highly reliable liquid crystal module.
For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings.